... what happens when you convert a JPEG into a DNG. Ain't raw data bud. ...
The approach of A.I. is not to convert (as you would do in LR), but to re-create data which is consistent with the output. Paraphrasing what Bart said a few posts ago, it is not trying to unscramble the egg, but having a taste of it and trying to recreate the recipe that would lead to the final plate (which a good chef would easily do, applying his knowledge and intelligence).
In an hypothetical scenario of having infinite computer power and infinite raw image and final jpeg samples under all imaginable cases, it would theoretically be possible to re-create (not convert) a "True raw" from a jpeg file using A.I.
We are very far from there, but let's for a moment consider that this is a newborn baby that has to grow and learn, so let's not kill him yet.
What I think is the problem is that Topaz marketing went crazy and oversold the product and its capabilities. Maybe they thought that it was necessary to sell the product, but the risk is that it could backfire and die prematurely. For instance, this is a quote from the Topaz web site:
JPEG to RAW’s machine learning models expand the sRGB colorspace to ProPhoto RGB, which is even better than a regular RAW file!
This is nonsense taken to a whole new level, at least that's what I think. Why do that? Unless the target of this product is not the knowledgeable crowd
Now, back to the tests, In my previous posts I showed that a Jpeg to Raw DNG is not even close to a Raw file with extreme underexposure, here is the result of trying to edit the underexposed jpeg compared to the A.I. generated DNG (in my opinion one is bad, the other is worse)
Trying to get shadow detail with the DNG generated from JPEG to RAW:
This with the original out of camera JPEG:
Another test, where the product shows improvement is in reducing JPEG artifacts: This is a coparison of an original rendered NEF, a low quality (full size) JPEG and a DNG generated from the JPEG. The DNG shows a big reduction of jpeg artifacts, reduced banding in the sky, at the expense of creation of artificial detail as can be seen in the church windows.
-- Edit: The following are 100% crops --
Original image from NEF:
JPEG full size, but low quality factor, (I'm not sure if the banding in the sky can be appreciated)
Finally, the DNG out of Jpeg to Raw:
IMHO this DNG is better than the JPEG but not better than the original.
I have made other tests with extremely off white balances, and no, you cannot get a DNG which can compare with the original raw. Some colors will be off, not matter what you do.
My conclusion: it is not a raw file, the application it is capable of creating a tiff file with better quality than the jpeg in some cases. Topaz is creating expectations that cannot be met, at least for now.